640 
president's address. 
mammals, and then we find all at once an abundance of highly 
differentiated marsupials with monotremes whose descendants com- 
paratively little changed in type we have around us at the present 
day. That these highly differentiated Australian types had no 
representation, so far as is known, outside Australia, except in the 
extreme south of the American continent, is a fact full of signifi- 
cance. 
It would appear then as if at the end of the Mesozoic period 
before the evolution of the higher orders of mammals took 
place there must have existed a territory already inhabited by 
marsupials, which then became cut off from the rest of the land to 
the north, and that in this land — a portion of the pre-existing 
Gondwana Land of Suess, or Antarctica of Forbes — the differen- 
tiation of the marsupials occurred, and that further this land, 
which may have been shifting in character, was at the end of the 
Miocene or beginning of the Pliocene, connected with Tasmania. 
Mr. C. Hedley's paper on the " Surviving Refugees of Antarctic 
Lands," read before the Royal Society of New South Wales last 
year, deserves thoughtful consideration. 
I have devoted some space to the above matter because it bears 
on the question of the origin of Australian Vegetation. It is 
clear that the peculiar Australian types could not have been immi- 
grants b} T the same route as the marsupials, or, indeed, immigrants 
at all, but the above considerations show the great probability of 
the existence of extensive land surfaces in the Antarctic regions 
at the end of the Mesozoic and in the earlier Tertiary times; that 
the connection with more northern lands was of a somewhat 
fleeting character, and that while it permitted of the passage of 
one element of the Australia Flora from South America to Tas- 
mania, the succession of these fluctuating land surfaces did not 
allow of any large migration of Australian types in the opposite 
direction. « 
In his " Introduction to the Flora of Tasmania," published in 
1860, Hooker sets forth the facts connected with the distribution 
of plant life in Australia and Antarctic lands. This able work 
is still the best complete treatise on the subject, and only requires 
